Just when Celtic thought their march towards a 100-point league campaign was only 90 minutes away, St Johnstone demonstrated why they could yet be the club’s first trophy winners in 130 years.

That they are a team of real mettle and no little courage was amply demonstrated by the manner in which they dug out a draw from a seemingly impossible position. With only seven minutes remaining they were 3-1 down, but a long-range drive from St Johnstone midfielder Scott Brown, which made the net via a deflection, put them on the front foot.

Inside 120 seconds, the scoreline was 3-3, after Michael O’Halloran headed in a David Wotherspoon cross from the right.

Before this flurry, Celtic had seemed to set themselves up to go into Sunday’s hosting of Dundee United looking for the win to take them on to 101 points. They made it 2-1 in 73 minutes when Alan Mannus pushed a cross out, it landed for Charlie Mulgrew and he smartly played it into the path of Teemu Pukki to lash in.

Celtic’s third followed four minutes later, with a blunderbuss of a first-time strike from Virgil van Dijk having appeared to put the visitors firmly in charge, and firmly on the way to yet one more win. The end that followed was in complete contrast to the beginning.

Then, the feel of a ‘so-what’ encounter was engendered not merely by the crowd numbering a modest 4,624. It was also betrayed by the line-ups both managers elected to field. For different reasons, each left about half of their first choice starters in reserve.

Yet, even with the Scottish Cup final clearly looming large in his mind, Tommy Wright still selected his goal machine, Stevie May. Perhaps May was sent out precisely because the 21-year-old is only three goals away from reaching the magic 30 mark, a tally that would be extraordinary for a mid-table team.

Celtic’s own 30-goal bagger, Kris Commons, was one of a clutch of regulars to which Neil Lennon gave rest-time – in the shape of a spot on the bench. Indeed, with Anthony Stokes, Leigh Griffiths and Scott Brown for company in tracksuit territory, the visitors’ goal threat was entrusted to the trio of summer signings who have provided all too little of that commodity.

It cost around £6 million to bring Amido Balde, Derk Boerrigter and Pukki to the Scottish champions. The fact that last night was the first time they had all been fielded together in a competitive game told its own story. Pukki and Balde had their moments as they both grafted away – the Finn forcing a block from Mannus – but couldn’t avoid looking like fill-in performers, until Pukki struck.

On that score, the tale of the first half was created by the men who have rarely been sighted in St Johnstone colours this season. The home side almost took the lead in 29 seconds with little-used Michael O’Halloran thumping the upright from long range. Within eight minutes they had claimed the opener that their early pressing merited when a Lee Croft corner was headed towards goal by Steven Anderson, and diverted into the net from close in by Tim Clancy.

The Irishman celebrated with gusto, and could be forgiven for doing so. His last goal was 20 months and another club ago, and with a bit of symmetry came when he playing against Celtic for Hibs.

The Perth club really should have put Celtic in a pickle when Beram Kayal tripped the impressive O’Halloran three minutes from the interval to earn them a penalty. Stand-in keeper Lukasz Zaluska guessed correctly to save May’s spot-kick low to his left. The striker’s night then went from bad to worse when he was hurt in a 50-50 challenge with Efe Ambrose and, worryingly, forced off at the interval, to be replaced by Nigel Hasselbaink.

In terms of personnel changes, the appearance of Kris Commons and Scott Brown for the second period was surely a comment from Lennon on the players he requires to lean on. The pair quickly showed their worth with a neat interchanged inside the St Johnstone box that ended with Gary McDonald clipping the Celtic captain and Commons then ramming home the penalty that ensued. What followed thereafter, no one could have envisaged.